Check robot description validity on AdmittanceController and test for it

[caio-freitas]

Fix #713

• Uncommented test case with "bad_robot" as robot description from test suite in test_admittance_controller.cpp.
• Updated the on_init on test_admittance_controller.hpp to only override the robot description with the one defined in the ros2_control_test_assets if not already defined.
• On the initialization of the admittance controller, verified if the robot description is a valid xml, similar to what's done in ros2_control/hardware_interface/src/component_parser.cpp (here)

[christophfroehlich]

Thank you for taking this. I have some doubts if this is tested properly, see the comments

[christophfroehlich]

Thinking again, is there really a need to check this inside the controller? The controller manager will not start with a broken urdf, right @saikishor ?

[saikishor]

I agree with @christophfroehlich that this is not needed as CM provides a valid one.

Can you explain to us, why did you have a need to do this?

[christophfroehlich]

see the linked issue, but this was before we passed the robot description from the cm to the controllers. sorry for not checking that earlier. @caio-freitas would you mind in reverting this and cleanup the tests as by my comments instead?

[christophfroehlich]

This has no effect, see the failing test

2: [ RUN      ] InvalidParameterDuringConfiguration/AdmittanceControllerTestParameterizedInvalidParameters.invalid_parameters/7
2: /workspaces/ros2_rolling_ws/src/ros2_controllers/admittance_controller/test/test_admittance_controller.cpp:73: Failure
2: Expected equality of these values:
2:   SetUpController()
2:     Which is: 1-byte object <00>
2:   controller_interface::return_type::ERROR
2:     Which is: 1-byte object <01>

Instead you have to get_parameter (to get it from the parameterized test suite) and override robot_description_ member variable, which will be used for controller_interface::ControllerInterfaceParams params in SetUpControllerCommon

[caio-freitas]

I've set the controller_->robot_description to the value passed to the parameter overrides before initializing the controller, since we don't have access to the overrides on TestableAdmittanceController::on_init(). Let me know if you agree with the approach.